Flow-controlling means for steam boilers



T. H. M GRAW, JR

Oct. 2 1923.

FLOW CONTROLLING MEANS FOR STEAM BOILERS Fi1ed Jan. 16 1920 I M J I I I 6; z2211 ff INVENTOR M. f v W V Patented (let. 2, 1923. 7

masses 1 g V Qirnoivres E. Maser-1w, i B QoF AKMorTT, mm m smapj I rtow oonr aoiininsmissus iron steer/ sornnnsfi 1 Application filed ma is, 1920. Serial no. 351,890. 5 I i To all whom it may concern.

Be it known that I, Tiroixms M'OGRAW; J12, a citizen of the United States,jand a resident of Oakmont, in the county 'of All gheny and State of 'Pennsylvaniayh ave" of water through the tubesof such boilers.

In all water tube boilers'there is a more or less clearly defined circulatioi'i' of water through the tubes. The direction and "in tensity of flow through each individual tube depends somewhat on the'arrangement and the location of the-tube and the amount' of heat to which the tube is'subjected under operatingconditions; For example, in a 7 three pass boiler the tubesof the first pass are subjected to the direct heat of 'theffu'rnace and ialso 'the initial -'flow of hot gases leaving the furnace. Consequently more steam is probably generated in these tubes,- and the upward flow or'oir'culation' throughtliem is more'intense than inother tubes of the boiler. The tubes of the'second pass are subjected to hot gaseswhich have only been partially cooled i'n'their' sage between the tubes of the firstpass and consequently the circulation is'probably-upward through all the-tubes ofthis pass: It is possible that a downwardcirculation may be maintained in such tubes of the second pass as are notlocated in the path ofthe direct flow of gas. The gases traversing the third pass are so reduced in temperature as to preclude the development of much, if any steam, and the circulation through the tubes of the third pass is unqualifiedly downward, andthe rate of flow depends to a large extent on the intensity of upward fiow through other tubes of the boiler, since the downward or return flow is induced by the upward flow. Where the boiler is being operated well above normal rating, the heat to which the tubes of the first pass are subjected occasions a violent generation of steam in those tubes and inasmuch as the steam is lighter than water it rises to the top, push-- ing the water ahead of it. The same condition may exist in certain tubes of the second or middle pass with the result that some of the tubes do not generate steam with maximum efficiency and with the further result that a certain: degree ofsfrothing'takes place and the boiler-has-a tendency to deliver wet steam, whereas, under normalconr. ditions of operation it would. deliver:- per-1 fcctly dry steam. My invention consistsin employing means; foncontrollirig' circulation or flow through tllGq tubes ofithe boiler,

so that-it will be possible to operaterthe boilerwith high 'efli'c-i'ency throughiawide range of operating conditions andso thatv the boiler will deliverdry-steambven-whil operating, at for example 4-0O%.rating.

In Figure 1 o'f the drawing-accompany" ing, formingthe part hereof, I have-unore or less-diagrammaticallyillustrated a Water tube boiler of a well known typefso equipped that it forms an embodiment ofmy-;invenj-' tion'; portions of the boiler are shown in,sec-. tionfor convenience of illustration. -Fi'gure 2- is a .fr agmental sectional view ofa' drum and boiler tube equippedwith a device embodying mydnventionxz- Figure 3 is plan view of the flow restricting device shown in Figure 2, -I v In carrying out-my' invention, I control theilow through the individual tubes of the boiler by reducing the efi'ective arealof the tubes; This is accomplished inthe illus-.

trated embodimentby partially restricting either the inlet or the i-outlet of each tube; In FiguresQ and -I have illustratedanem bodiment of the invention which-consistsot 5 a cap or plug for the tube which is provided with an opening or passage of such zar'ea 9 with relation to the area of :the tube to which it is attached as to occasion the desired restriction of flow through-the tube. For example, those tubesof the first pass which are'subjeoted to the greatest flow of hot gas through the furnace and which are consequently subjected to violent generation of steam while the boiler is being forced orv operated materially above normal rating, will preferably be provided with caps at their upper end for the purpose of prevent ing the. steam from causing. an undue acceleration of the water passing through the tube and thereby causing excessive agitation v in the drum which results inthe delivery of wet steam. Likewise, certainof the tubes of the second p'ass may be equipped with such a flow restricting device to prevent an excessive upward flow through them, and it may be desirable to fit the-restricting dev vices to the lower instead of the upp end of these tubes,

7 that my invention makes it possible to tioning'the effective area of some'or all of It will be apparent from the foregoing modify and thereby control the flow through the tubes under the normal'as well as abnormal conditions of operation and that the flow restricting devices maybe so proportionedwith relation to the areas of their cooperating tubes that the rate of flow may be maintained substantially uniform through all. the tubes-on through certain groups of tubesby reducing and proporthe tubes of the boiler or of the group in question 7 While it; will be apparent that these results'maybe obtained by "locating flow restricting devices at different points in the 1 individual tubes, Figures 2-and 3illustrate means for capping an end of a tube and in Ithis way restricting the'fiowthrough it. As

illustrated in Figure 2, the cap consists of a metal disc 5 having a central aperture 6 V: adapted'to be secured to the. flared portion of the tube 7, which projects through the shell 8 of" the drum. Itfwill be apparent thatthe sizeof the aperture 6 will depend upon the diameter ofthe tube on which the' plate ;5 is ,fitted and also upon the desired portion of the flared end of the tube which.

projects beyond the plate of which the drum is formed. It will be apparent that Where caps similarito the cap 5 are employed, any convenient means may be employed for securing'the disc in place. i

In Figure 1, I have shown a water tube boiler of a well known type equipped with caps's uchas'aie illustrated in Figures 2 and 3. As illustrated, the upper ends of the tubes 7 of the first pass are equipped with the caps 5, Whereas the lower ends of the tubes 7' are so equipped. The tubes 7" of the second pass are equipped-withcaps 5 at their lower ends. While I have shown the tubes ofthe third pass without the flow re- L stricting devices, it will be apparent that one or more rows of this pass or even certain tubes of thispass maybe s 0 equipped, since I contemplate employing the ,fiow re stricting devices to, thebest advantage for the purpose of producing the. desired conv ditions offlow, I

From the foregoing, that various changes, modifications,v additions and omissions may be made in the apparatus illustrated without departing from the spirit, and scope of the invention as set forth by the appended claims.

hat-I claim isz u V 1. In combination in a water tube boiler, steam and water drums, water tubes con nectingsaid drums,- anda flow-restricting device for certain ofsaid tubes, eachg de vice consisting of a cap located in the drum and fitted over'the end of a tube andhav ing an aperture formed' therein-oi less diam? it wi l be a arent eter than the, passages through the tube and.

integrally formed fingers forced. into engagement' with the end of'the tube.

' 2.3 In-combination in a water tube boiler, steam and waterv drums, water tubes connecting the drums, and flow restricting .de-,

vices associated with certain of said tubes, each device comprising a cap located over the end of a tube and positively secured in place by means. of integrally formed fingers bent into engagement :with the exterior surface ofJ-theend of the tube.

Intestimony whereof, I havejhereunto subscribed myname this 14th day of January,1920. k v

THOMAS MGGRAW, JR. 

